The primary uses of simvastatin are for the treatment of dyslipidemia and the prevention of cardiovascular disease.[2] It is recommended to be used only after other measures such as diet, exercise, and weight reduction have not improved cholesterol levels sufficiently.[2]

Possible side effects include: muscle breakdown, liver problems, and increased blood sugar levels, among others.[2] It is pregnancy category X in the United States and category D in Australia meaning that there is evidence of harm to a baby when taken by pregnant women.[2][3] It should not be used by those who are breastfeeding.[2]

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Medical uses[edit]

The primary uses of simvastatin are for the treatment of dyslipidemia and the prevention of cardiovascular disease.[2] It is recommended to be used only after other measures such as diet, exercise, and weight reduction have not improved cholesterol levels sufficiently.[2]

Adverse effects[edit]

Common side effects (>1% incidence) may include abdominal pain, diarrhea, indigestion, and a general feeling of weakness. Rare side effects include joint pain, memory loss, and muscle cramps.[6] Cholestatic hepatitis, hepatic cirrhosis, rhabdomyolysis (destruction of muscles and blockade of renal system), and myositis have been reported in patients receiving the drug chronically.[7] Serious allergic reactions to simvastatin are rare.[8] If the following signs of a serious allergic reaction occur, seek medical attention immediately: rash, hoarsness itching/swelling, dizziness, or difficulty swallowing/breathing.[8]

A type of DNA variant known as a single nucleotide polymorphism (SNP) may help predict individuals prone to developing myopathy when taking simvastatin; a study ultimately including 32,000 patients concluded the carriers of one or two risk alleles of particular SNPs[9] were at a five-fold or 16-fold increased risk, respectively.[10]

In March 2012, the FDA updated its guidance for statin users to address reports of memory loss, liver damage, increased blood sugar, development of type 2 diabetes, and muscle injury.[13] The new guidance indicates:

FDA has found that liver injury associated with statin use is rare but can occur.

The reports about memory loss, forgetfulness, and confusion span all statin products and all age groups. Egan says these experiences are rare but that those affected often report feeling “fuzzy” or unfocused in their thinking.

A small increased risk of raised blood sugar levels and the development of type 2 diabetes have been reported with the use of statins.

Some drugs interact with statins in a way that increases the risk of muscle injury called myopathy, characterized by unexplained muscle weakness or pain.

This advice has caused some controversy, and claims have been made that it is too conservative in its guidance regarding diabetes. In March 2012, Eric J. Topol, the Chief Academic Officer for Scripps Health and Director, Scripps Translational Science Institute, published an op-ed piece in the New York Times entitled "The Diabetes Dilemma for Statin Users",[14] claiming the trial data had been misunderstood and the risk of diabetes among users of simvistatin, atorvastatin, and rosuvastatin was much higher.

On March 19, 2010, the FDA issued another statement regarding simvastatin, saying it increases the risk of muscle injury (myopathy) when taken at high doses or at lower doses in combination with other drugs.[15] The highest dose rate causes muscle damage in 610 of every 10,000 people in contrast to a lower dose, which causes muscle damage in eight of 10,000 people.[16] The FDA warning, released again on June 8, 2011, suggested that high dose "simvastatin should be used only in patients who have been taking this dose for 12 months or more without evidence of muscle injury" and that it "should not be started in new patients, including patients already taking lower doses of the drug."[17]

Cost[edit]

Simvastatin was introduced in the late 1980s, and since 2006 in many countries, it is available as a generic preparation. This has led to a decrease of the price of most statin drugs, and a reappraisal of the health economics of preventive statin treatment. In the UK in 2008, the typical per-patient cost to the NHS of simvastatin was about £1.50 per month.[18] (40 mg/day costs UK NHS £1.37/month in 2012[19])

Pharmacology[edit]

All statins act by inhibiting 3-hydroxy-3-methylglutaryl coenzyme A HMG-CoA reductase, the rate-limitingenzyme of the HMG-CoA reductase pathway, the metabolic pathway responsible for the endogenous production of cholesterol. Statins are more effective than other lipid-regulating drugs at lowering LDL-cholesterol concentration, but they are less effective than the fibrates in reducing triglyceride concentration. However, statins reduce cardiovascular disease events and total mortality irrespective of the initial cholesterol concentration. This is a major piece of evidence that statins work in another way than the lowering of cholesterol (called pleiotropic effects).[21]

Interactions[edit]

Simvastatin has important interactions with grapefruit juice and other drugs, including some that are commonly used for the treatment of cardiovascular disease. These interactions are clinically important because increasing simvastatin serum levels above those normally provided by the maximum recommended dose increases the risk of muscle damage, including the otherwise rare and potentially fatal side effect of rhabdomyolysis.[22]

Consuming large amounts of grapefruit juice increases serum levels of simvastatin by up to three-fold, increasing the risk of side effects.[23][24][25][26] The FDA recommends that people taking statins should avoid consuming more than a quart of grapefruit juice per day.[22]

Contraindications[edit]

Simvastatin is contraindicated with pregnancy, breastfeeding, and liver disease.[8] Pregnancy must be avoided while on simvastatin due to potentially severe birth defects. Patients cannot breastfeed while on simvastatin due to potentially disrupting the infant's lipid metabolism.[28] High doses of simvastatin are also contraindicated with the widely used antihypertensive amlodipine.[29] A lower dose is also recommended in people taking the calcium channel blockers, verapamil and diltiazem, as well as those taking amiodarone.[30]

Marketing[edit]

Simvastatin was initially marketed by Merck & Co under the trade name Zocor, but is available generically in most countries following the patent expiry. A combination of simvastatin along with ezetimibe is sold under the brand name Vytorin and is jointly marketed by Merck and Schering-Plough.

Sales[edit]

Prior to losing U.S. patent protection, simvastatin was Merck & Co.'s largest-selling drug and second-largest-selling cholesterol lowering drug in the world. In 2005, recorded US$3.1 billion of sales in the US and US$4.4 billion worldwide.[31]

Zocor had an original patent expiry date of January 2006, but was extended by the United States Patent Trademark Office (PTO) to expire on June 23, 2006.[citation needed] The PTO granted the patent extension after Merck submitted data from studies of the drug’s positive effect on children, a move typically used by drug companies to lengthen exclusivity. In the UK, the patent for simvastatin had expired by 2004.[citation needed]

Ordinarily, Merck would have expected a sharp decrease in sales after the generic versions of simvastatin entered the market. However, Merck has slashed the price of Zocor dramatically in an effort to claim sales that would have otherwise gone to the generic versions.[citation needed][32] At least two major U.S. health insurers, UnitedHealthcare and WellPoint, are offering Zocor to their members as generic copays.[33]

In addition, since Merck manufactures some versions of Dr. Reddy's authorized generic simvastatin,[citation needed] Merck is poised to profit from Dr. Reddy's version. An 80-mg, 30-count bottle of Dr. Reddy's simvastatin obtained July 6, 2006, states it is made by Merck Sharp & Dohme (Merck & Co.'s name outside the U.S. to avoid conflicts with Merck KGaA) in the UK, just like 80-mg Zocor, and has a Merck & Co. logo on the bottom; except for omitting the "80" on one side, the tablets are visually identical to Zocor, including "543" on the other side which is the key part of the National Drug Code for 80-mg Zocor.[citation needed]

In the UK, simvastatin is the most prescribed medication in the community, with 39.9 million items dispensed in 2013. This compares to 30.9 million items for aspirin, and 27.7 million for levothyroxine sodium, the second and third most prescribed drugs in the UK in 2013.[34]

History[edit]

The development of simvastatin was closely linked with lovastatin. Biochemist Jesse Huff and his colleagues at Merck began researching the biosynthesis of cholesterol in the early 1950s.[35] In 1956, mevalonic acid was isolated from a yeast extract by Karl Folkers, Carl Hoffman, and others at Merck, while Huff and his associates confirmed that mevalonic acid was an intermediate in cholesterol biosynthesis. In 1959, the HMG-CoA reductase enzyme (a major contributor of internal cholesterol production) was discovered by researchers at the Max Planck Institute. This discovery encouraged scientists worldwide to find an effective inhibitor of this enzyme.[citation needed]

By 1976, Akira Endo had isolated the first inhibitor, mevastatin, from the fungusPenicillium citrinium in Sankyo, Japan.[36] In 1979, Hoffman and colleagues isolated lovastatin from a strain of the fungus Aspergillus terreus. While developing and researching lovastatin, Merck scientists synthetically derived a more potent HMG-CoA reductase inhibitor from a fermentation product of A. terreus, which was designated MK-733 (later to be named simvastatin).[4]

^Steve Sternberg (2011-06-09). "Simvastatin can damage muscles in high doses". USA Today. Retrieved 2011-06-09. The cholesterol-lowering drug simvastatin can cause severe muscle damage and should not be prescribed in high doses to patients who have taken it for less than a year or in any dose to people taking certain drugs, health officials said Tuesday. . . . Research has shown that the highest dose of simvastatin, 80 milligrams, causes muscle damage in 61 of every 1,000 patients, far higher than the eight-per-10,000 rate in patients taking a 40-milligram dose, Rosenblatt says.